Suitability of a Novel Circulating Cooling SPME for Analysis of Organophosphorous Pesticides in Tomatoes

Abstract

The feasibility of circulating cooling-solid phase microextraction (CC-SPME) combined with gas chromatography-nitrogen phosphorous detector (GC-NPD) for the determination of five organophosphorous pesticides (OPPs) in tomato samples is evaluated. By heating the sample while cooling the fiber coating, the developed method provides better performance in terms of sensitivity, linearity and recovery than that of traditional headspace-solid phase microextraction (HS-SPME). The extraction capacities of activated carbon fiber (ACF) and three commercially available fibers were compared. ACF is found to be the most suitable fiber for the analysis of OPPs in tomatoes. The main factors affecting the CC-SPME process such as adsorption time, adsorption temperature and ionic strength were investigated and optimized. The matrix effect was evaluated, and concluded that addition of water is required to reduce the matrix effect. Good linearity (R2 > 0.992) is observed in the 1–200 ng g−1 concentration range with satisfactory RSD (%) values of 5.6–8.5%. The limits of detection obtained using the proposed method range from 0.2 to 0.5 ng g−1, and the recoveries for CC-SPME are in the range of 82.5–90.0% with RSDs lower than 8.7%. Experimental results confirm the usefulness of the proposed method for the analysis of OPPs in tomato samples.